Round bender

ABSTRACT

A round bender is disclosed. The round bender may include a plurality of bending roll units disposed along a process line between a pair of bender frames so as to bend a straight shaped beam to have a curvature. Each of the plurality of bending roll units may include upper and lower bending rolls rotating between the pair of bender frames and may be adapted to bend the shaped beam to have the curvature when the shaped beam passes between the upper and lower bending rolls. A lower bending roll of a rearmost bending roll unit disposed on a rearmost part of the process line may be configured to be rotatable with reference to an upper bending roll of the rearmost bending roll unit so as to change a curvature radius of some portion of the shaped beam.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application Nos. 10-2012-0052036 and 10-2012-0052037 filed in the Korean Intellectual Property Office on May 16, 2012, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a round bender. More particularly, the present invention relates to a round bender that bends an end portion of the shaped beam having a predetermined curvature to have another curvature different from the predetermined curvature.

(b) Description of the Related Art

Generally, a product having a predetermined curvature such as a bumper beam for vehicles is manufactured by bending, after a straight shaped beam is formed by roll forming method, the straight shaped beam to have the predetermined curvature by means of a round bender.

According to roll forming method, a coil is uncoiled and the uncoiled coil is bent to various shapes by passing a roll former unit. The roll former unit includes a plurality of roll formers that are sequentially disposed, and each roll former is provided with an upper forming roll and a lower forming roll. The roll forming method is used for manufacturing beams of linear type (particularly, a bumper beam for a vehicle) which is bent to the various shapes.

FIG. 1 is a schematic diagram of a typical roll forming system and steps of a roll forming method.

Referring to FIG. 1, the typical roll forming system and method thereof includes an uncoiler 1 at a front portion of a process line, and the uncoiler 1 performs an uncoil step S1 at which a coil 10 is uncoiled.

A straightener 2 is provided at the rear of the uncoiler 1 in the process line and performs a straightening step S2 at which the coil 10 uncoiled from the uncoiler 1 is straightened to a panel 20 of plate shape.

A brake press 3 is disposed at the rear of the straightener 2 in the process line and performs a piercing step S3 at which a plurality of holes for assembling is formed at the panel 20 supplied from the straightener 2.

A roll forming unit 4 including at least seven roll formers R1-R7 is disposed at the rear of the brake press 3 in the process line. The roll forming unit 4 performs a roll forming step S4 at which the panel 20 passing through the uncoiler 1, the straightener 2, and the brake press 3 is sequentially bent such that a shaped beam 30 is formed.

A laser welding device 5 is disposed at the rear of the roll forming unit 4 in the process line and performs a welding step S5 at which a laser beam outputting from a laser oscillator 5 a is irradiated to a welding portion of the shaped beam 30.

In addition, a round bender 6 is provided at the rear of the laser welding device 5 in the process line and performs a bending step S6. At the bending step S6, the shaped beam 30 passes through the round bender 6 such that the shaped beam 40 having the curvature is formed.

A cutting press 7 for cutting the shaped beam 40 to have a dimension of product is provided at the rear of the round bender 6 in the process line, and performs a cutting step S7.

FIG. 2 is a side view of a typical round bender.

Referring to FIG. 2, the round bender 6 includes five bending roll units.

A first bending roll unit BR1 includes upper and lower bending rolls and is disposed at a front portion on a bender frame 6 a in the process line. The first bending roll unit BR1 guides the shaped beam 30 passing through the welding step S5.

A second bending roll unit BR2 includes upper and lower bending rolls and is disposed at the rear of the first bending roll unit BR1 on the roll frame 6 a. The second bending roll unit BR2 slidably supports the shaped beam 30 along the curvature direction.

In addition, third, fourth, and fifth bending roll units BR3, BR4, and BR5 are sequentially disposed at the rear of the second bending roll unit BR2 on the roll frame 6 a along the curvature and respectively include upper and lower bending rolls.

The shaped beam 30 passes through the third, fourth, and fifth bending roll units BR3, BR4, and BR5 sequentially such that the shaped beam 40 having the curvature is formed.

A bumper beam 50 for vehicles shown in FIG. 3 is manufactured by the roll forming system and the roll forming method.

The bumper beams 50 are disposed at a front portion and a rear portion of the vehicle along a width direction of the vehicle, and are connected to a front side member (not shown) through a stay (not shown).

A bumper beam 50 having multiple curvatures is used for classy design of the vehicle and preventing interference with other components of a bumper unit.

In the bumper beam 50 having the multiple curvatures, as shown in FIG. 3, curvature radii of both end portions is smaller than that of a middle portion.

That is, the bumper beam 50 includes a first curvature portion 51 having a first curvature radius that is the same as the predetermined curvature and a second curvature portion 52 disposed at both end portions of the first curvature portion 51 and having a second curvature radius different from the first curvature radius.

Since the conventional round bender 6 shown in FIG. 2, however, can form the shaped beam 40 having one curvature, an additional bending step should be performed by means of an additional bending unit so as to form the second curvature portions 52 at the both end portions of the bumper beam 50 shown in FIG. 3.

Therefore, manufacturing processes for the bumper beam, manufacturing cost, and installation cost for installing the additional bending unit may increase.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to provide a round bender having advantages of manufacturing a shaped beam having a first curvature portion and a second curvature portion without mounting an additional bending unit by improving a conventional round bender.

A round bender according to an exemplary embodiment of the present invention may include a plurality of bending roll units disposed along a process line between a pair of bender frames so as to bend a straight shaped beam to have a curvature.

Each of the plurality of bending roll units may include upper and lower bending rolls rotating between the pair of bender frames and may be adapted to bend the shaped beam to have the curvature when the shaped beam passes between the upper and lower bending rolls.

A lower bending roll of a rearmost bending roll unit disposed on a rearmost part of the process line may be configured to be rotatable with reference to an upper bending roll of the rearmost bending roll unit so as to change a curvature radius of some portion of the shaped beam.

The round bender may further include a curvature changing means rotating the lower bending roll of the rearmost bending roll unit with reference to the upper bending roll of the rearmost bending roll unit, wherein the curvature changing means are disposed at the rearmost bending roll unit between the pair of bender frames such that a rotational shaft of the upper bending roll is rotatably supported at the pair of bender frames, and a rotational shaft of the lower bending roll is movably disposed in a penetration hole formed at the pair of bender frames.

The curvature changing means may include: a cylinder disposed at a middle portion above the pair of bender frames, and hinged to the pair of bender frames through a hinge bracket; and a rotating fork having an upper end hinged to a rod of the cylinder, and connected to the rotational shafts of the upper and lower bending rolls of the rearmost bending roll unit at an outer of the pair of bender frames so as to rotate the rotational shaft of the lower bending roll in the penetration hole with respect to the rotational shaft of the upper bending roll according to operation of the cylinder.

The rotating fork may include: a connecting bar disposed above the pair of bender frames and having a hinge end protruded from a middle portion of an upper surface of the connecting bar and hinged to the rod of the cylinder; and a pair of rotating bars disposed at the outer of the pair of bender frames corresponding to the rearmost bending roll unit, wherein an upper end of the rotating bar is connected to an end of the connecting bar, the rotational shaft of the upper bending roll is rotatably mounted at an upper portion of the rotating bar, and a slide hole is formed at a lower portion of the rotating bar such that the rotational shaft of the lower bending roll is rotatably mounted at a slider slidably mounted in the slide hole.

The rotational shaft of the upper bending roll may be rotatably mounted at a sliding block slidably mounted in a slide recess formed at an upper portion of the bender frame.

A round bender according to another exemplary embodiment of the present invention may bend a straight shaped beam to have a curvature.

The round bender may include: a pair of bender frames mounted apart from each other on both sides of a base; a first bending roll unit including an upper bending roll and a lower bending roll, disposed at a front portion on a process line between the pair of bender frames, and guiding the shaped beam; a second bending roll unit including an upper bending roll and a lower bending roll, disposed at the rear of the first bending roll unit between the pair of bender frames, and slidably supporting the shaped beam along a curvature direction; third, fourth, and fifth bending roll units respectively including an upper bending roll and a lower bending roll, sequentially disposed at the rear of the second bending roll unit between the pair of bender frames along the curvature, and forming the shaped beam to have a predetermined curvature when the shaped beam passes therethrough; and a curvature changing means disposed between the bender frame and the fifth bending roll unit and rotating the lower bending roll of the fifth bending roll unit with reference to the upper bending roll of the fifth bending roll unit so as to change a curvature radius of some portion of the shaped beam.

The curvature changing means may be mounted at the fifth bending roll unit between the pair of bender frames such that a rotational shaft of the upper bending roll is rotatably supported at the pair of bender frames, and a rotational shaft of the lower bending roll is movably disposed in a penetration hole formed at the pair of bender frames.

The curvature changing means may include: a cylinder disposed at a middle portion above the pair of bender frames, and hinged to the pair of bender frames through a hinge bracket; and a rotating fork having an upper end hinged to a rod of the cylinder, and connected to the rotational shafts of the upper and lower bending rolls of the fifth bending roll unit at an outer of the pair of bender frames so as to rotate the rotational shaft of the lower bending roll in the penetration hole with respect to the rotational shaft of the upper bending roll according to operation of the cylinder.

The rotating fork may include: a connecting bar disposed above the pair of bender frames and having a hinge end protruded from a middle portion of an upper surface of the connecting bar and hinged to the rod of the cylinder; and a pair of rotating bars disposed at the outer of the pair of bender frames corresponding to the fifth bending roll unit, wherein an upper end of the rotating bar is connected to an end of the connecting bar, the rotational shaft of the upper bending roll is rotatably mounted at an upper portion of the rotating bar, and a slide hole is formed at a lower portion of the rotating bar such that the rotational shaft of the lower bending roll is rotatably mounted at a slider slidably mounted in the slide hole.

The rotational shaft of the upper bending roll of the fifth bending roll unit may be rotatably mounted at a sliding block slidably mounted in a slide recess formed at an upper portion of the bender frame.

A round bender according to other exemplary embodiment of the present invention may include at least three bending roll units disposed along a process line between a pair of bender frames so as to bend a straight shaped beam and including upper and lower bending rolls.

A lower bending roll of a rearmost bending roll unit on a process line may be configured to be rotatable with reference to an upper bending roll of the rearmost bending roll unit so as to change a curvature radius of some portion of the shaped beam.

The round bender may further include a curvature changing means rotating the lower bending roll of the rearmost bending roll unit with reference to the upper bending roll of the rearmost bending roll unit, wherein the curvature changing means are disposed at the rearmost bending roll unit between the pair of bender frames such that a rotational shaft of the upper bending roll is rotatably supported at the pair of bender frames, and a rotational shaft of the lower bending roll is movably disposed in a penetration hole formed at the pair of bender frames.

The curvature changing means may include: a cylinder disposed at a middle portion above the pair of bender frames, and hinged to the pair of bender frames through a hinge bracket; and a rotating fork having an upper end hinged to a rod of the cylinder, and connected to the rotational shafts of the upper and lower bending rolls of the rearmost bending roll unit at an outer of the pair of bender frames so as to rotate the rotational shaft of the lower bending roll in the penetration hole with respect to the rotational shaft of the upper bending roll according to operation of the cylinder.

The rotating fork may include: a connecting bar disposed above the pair of bender frames and having a hinge end protruded from a middle portion of an upper surface of the connecting bar and hinged to the rod of the cylinder; and a pair of rotating bars disposed at the outer of the pair of bender frames corresponding to the rearmost bending roll unit, wherein an upper end of the rotating bar is connected to an end of the connecting bar, the rotational shaft of the upper bending roll is rotatably mounted at an upper portion of the rotating bar, and a slide hole is formed at a lower portion of the rotating bar such that the rotational shaft of the lower bending roll is rotatably mounted at a slider slidably mounted in the slide hole.

The rotational shaft of the upper bending roll may be rotatably mounted at a sliding block slidably mounted in a slide recess formed at an upper portion of the bender frame.

In one or more exemplary embodiments of the present invention, the round bender may further include power delivery means mounted at the lower bending rolls of the bending roll units and delivering power therebetween.

In one or more exemplary embodiments of the present invention, position detecting means for detecting a position of a slider block is disposed between the sliding block used at the fifth bending roll unit or the rearmost bending roll unit and the bender frame guiding the sliding block.

The position detecting means may include: a marking needle mounted at the sliding block; and a graduated ruler attached to the bender frame corresponding to the marking needle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a typical roll forming system and steps of a roll forming method.

FIG. 2 is a side view of a typical round bender.

FIG. 3 is a perspective view of a typical bumper beam.

FIG. 4 is a perspective view of a round bender according to an exemplary embodiment of the present invention.

FIG. 5 is another perspective view of a round bender according to an exemplary embodiment of the present invention.

FIG. 6 is a partially projected perspective view of a round bender according to an exemplary embodiment of the present invention.

FIG. 7 is a partial cross-sectional view of a round bender according to an exemplary embodiment of the present invention.

FIG. 8 to FIG. 10 are schematic diagrams for showing operation of curvature changing means applied to a round bender according to an exemplary embodiment of the present invention.

<Description of symbols> 1: uncoiler 2: straightener 3: brake press 4: roll forming unit 5: laser welding device 6: round bender 7: cutting press 10: coil 20: panel 30, 40: shaped beam 50: bumper beam 51: first curvature portion 52: second curvature portion 61: base 63: bender frame 65: curvature changing means 67: connecting pipe 71: cylinder 73: rotating fork 75: hinge bracket 77: connecting bar 79: rotating bar 80: position detecting means 81: rod 83: hinge end 85: hinge fork 87: marking needle 89: graduated ruler 90: stopper 91: stopper ring 93: stopper rod BR1-BR5: first to the fifth bending roll units UR1-UR5: first to the fifth upper bending rolls LR1-LR5: first to the fifth lower bending rolls S: rotational shaft SG: slide recess SR: slider AB: adjusting bolt MB: movable block SH: slide hole BU: bearing unit H: penetration hole SP: sprocket C: chain

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

For clarifying description of an exemplary embodiment of the present invention, descriptions not related to the exemplary embodiment of the present invention will be omitted.

In the detailed description, ordinal numbers are used for distinguishing constituent elements having the same terms, and have no specific meanings.

A round bender 6 according to an exemplary embodiment of the present invention is used in a roll forming system shown in FIG. 1 and bends a straight shaped beam 30 formed by roll forming to have a curvature.

That is, referring to FIG. 1, a roll forming system and method thereof to which the round bender 6 according to an exemplary embodiment of the present invention is applied includes an uncoiler 1 at a front portion of a process line, and the uncoiler 1 performs an uncoil step S1 at which a coil 10 is uncoiled.

A straightener 2 is provided at the rear of the uncoiler 1 in the process line and performs a straightening step S2 at which the coil 10 uncoiled from the uncoiler 1 is straightened to a panel 20 of plate shape.

A brake press 3 is disposed at the rear of the straightener 2 in the process line and performs a piercing step S3 at which a plurality of holes for assembling is formed at the panel 20 supplied from the straightener 2.

A roll forming unit 4 including at least seven roll formers R1-R7 is disposed at the rear of the brake press 3 in the process line. The roll forming unit 4 performs a roll forming step S4 at which the panel 20 passing through the uncoiler 1, the straightener 2, and the brake press 3 is sequentially bent such that a shaped beam 30 is formed.

A laser welding device 5 is disposed at the rear of the roll forming unit 4 in the process line and performs a welding step S5 at which a laser beam outputting from a laser oscillator 5 a is irradiated to a welding portion of the shaped beam 30.

The round bender 6 according to an exemplary embodiment of the present invention is disposed at the rear of the laser welding device 5 in the process line and performs a bending step S6. At the bending step S6, the shaped beam 40 having different curvatures at a middle portion and both end portions thereof is formed while the shaped beam 30 passes through the round bender 6.

A cutting press 7 for cutting the shaped beam 40 to have a dimension of product is provided at the rear of the round bender 6 in the process line, and performs a cutting step S7.

Therefore, a bumper beam 50 shown in FIG. 3 including a first curvature portion 51 having a first curvature radius at the middle portion thereof and a second curvature portion 52 having a second curvature radius smaller than the first curvature radius at both end portions thereof is manufactured by the roll forming system and method thereof to which the round bender 6 according to an exemplary embodiment of the present invention is applied.

FIG. 4 and FIG. 5 are perspective views of a round bender according to an exemplary embodiment of the present invention; FIG. 6 is a partially projected perspective view of a round bender according to an exemplary embodiment of the present invention; and FIG. 7 is a partial cross-sectional view of a round bender according to an exemplary embodiment of the present invention.

Referring to FIG. 4 to FIG. 6, the round bender 6 according to an exemplary embodiment of the present invention includes five bending roll units BR1-BR5, and bends the straight shaped beam 30 formed by roll forming to have the curvature. The round bender 6 according to an exemplary embodiment of the present invention includes five bending roll units BR1-BR5, but is not limited thereto.

The round bender 6 according to an exemplary embodiment of the present invention includes a base 61, a pair of bender frames 63, the first to the fifth bending roll units BR1-BR5 disposed along the process line and curvature changing means 65.

The base 61 is mounted on a mounting table of the roll forming system along the process line, and the pair of bender frames 63 is mounted on both sides of the base 61 along the process line and is disposed apart from each other.

The pair of bender frames 63 are connected so as to maintain a distance therebetween through a plurality of connecting pipes 67. In addition, slide recesses SG are formed at a pair of bender frame 63, and sliders SR is slidably mounted in the slide recesses SG.

Referring to FIG. 4 to FIG. 7, the first bending roll unit BR1 includes a first upper bending roll UR1 and a first lower bending roll LR1, and is disposed at a front portion of the process line between the pair of bender frames 63. The first bending roll unit BR1 guides the shaped beam 30.

Each of the first upper bending roll UR1 and the first lower bending roll LR1 includes a rotational shaft S, and both ends of the rotational shaft S is rotatably mounted at the sliders SR mounted in the slide recesses SG.

The second bending roll unit BR2 includes a second upper bending roll UR2 and a second lower bending roll LR2, and is disposed at the rear of the first bending roll unit BR1 between the pair of bender frames 63. The second bending roll unit BR2 slidably supports the shaped beam 30 along a curvature direction.

Each of the second upper bending roll UR2 and the second lower bending roll LR2 includes a rotational shaft S, and both ends of the rotational shaft S is roatatbly mounted at the sliders SR mounted in the slide recesses SG.

Herein, the sliders SR used at the first bending roll unit BR1 and the second bending roll unit BR2 is divided into an upper slider and a lower slider, and each of the sliders SR is fixed to the slide recess SG of the bender frame 63 through an adjusting bolt AB. A position of the slider SR can be adjusted by means of the adjusting bolt AB.

The third, fourth, and fifth bending roll units BR3, BR4, and BR5 respectively include a third upper bending roll UR3 and a third lower bending roll LR3, a fourth upper bending roll UR4 and a fourth lower bending roll LR4, and a fifth upper bending roll UR5 and a fifth lower bending roll LR5, and are sequentially disposed at the rear of the second bending roll unit BR2 between the pair of bender frames 63 along the curvature. The shaped beam 30 is formed to have a predetermined curvature while passing through the third, fourth, and fifth bending roll units BR3, BR4, and BR5.

Herein, each of the third and fourth lower bending rolls LR3 and LR4 include a rotational shaft S, and both ends of the rotational shaft S are rotatably mounted at lower portions of movable blocks MB slidably mounted in the slide recesses SG. In addition, each of the third and fourth upper bending rolls UR3 and UR4 includes a rotational shaft S, and both ends of the rotational shaft S are rotatably mounted at the sliders SR slidably mounted in slide holes SH formed at upper portions of the movable blocks MB.

In addition, referring to FIG. 6, the fifth upper bending roll UR5 includes a rotational shaft S, and both end portions of the rotational shaft S is rotatably mounted through bearing units BU at sliding blocks SB slidably mounted in the slide recesses SG formed at upper portions of the bender frames 63. In addition, the fifth lower bending roll LR5 includes a rotational shaft S, and the rotational shaft S is movably disposed in a process line direction through penetration holes H formed at lower portions of the bender frames 63.

Herein, both ends of the rotational shaft S of the fifth lower bending roll LR5 are rotatably supported by the curvature changing means 65. The curvature changing means 65 are disposed between the bender frames 63 and the fifth bending roll unit BR5 so as to rotate the fifth lower bending roll LR5 in the penetration hole H with reference to the fifth upper bending roll UR5 by a predetermined angle. Therefore, the curvature changing means 65 moves to the fifth lower bending roll LR5 such that curvature radius of both end portions of the shaped beam 30 formed to have the curvature becomes smaller.

That is, the curvature changing means 65 include a cylinder 71 and a rotating fork 73. The cylinder 71 is disposed at a middle portion above the pair of bender frames 63. The cylinder 71 is hinged to the pair of bender frames 63 through a hinge bracket 75.

Herein, the cylinder 71 may be a hydraulic pressure cylinder, but is not limited thereto. Operating pressure of the hydraulic pressure cylinder is hydraulic pressure.

An upper end of the rotating fork 73 is hinged to a rod 81 of the cylinder 71. The rotating fork 73 is connected to the rotational shafts S of the fifth upper bending roll UR5 and the fifth lower bending roll LR5 at an outer of the pair of bender frames 63 so as to rotate the rotational shaft S of the fifth lower bending roll LR5 in the penetration hole H with reference to the rotational shaft S of the fifth upper bending roll UR5 according to operation of the cylinder 71.

The rotating fork 73 includes a connecting bar 77 and two rotating bars 79. The connecting bar 77 is disposed above the pair of bender frames 63 along a width direction. A hinge end 83 is protruded from a middle portion of an upper surface of the connecting bar 77, and the hinge end 83 is hinged to the rod 81 of the cylinder 71 through a hinge fork 85.

In addition, the two rotating bars 79 are disposed at an outer of the pair of bender frames 63 corresponding to the fifth bending roll unit BR5, and an upper end of each of the rotating bars 79 is connected to each of both ends of the connecting bar 77.

Both ends of the rotational shaft S of the fifth upper bending roll UR5 are mounted at upper portions of the rotating bars 79 through bearing units BU, and a slide hole SH is formed at a lower portion of each of the rotating bars 79. A slider SR is slidably mounted in the slide hole SH, and both ends of the rotational shaft S of the fifth lower bending roll LR5 are rotatably mounted at the sliders SR.

That is, the rotating fork 73 rotates the rotational shaft S of the fifth lower bending roll LR5 with reference to the rotational shaft S of the fifth upper bending roll UR5 according to forward/rearward operation of the cylinder 71 so as to change a position of the fifth lower bending roll LR5 to the fifth upper bending roll UR5. Therefore, the shaped beam is bent to have multiple curvatures such that curvature radius of some portion of the shaped beam 30 is different from that of other portion of the shaped beam 30.

Referring to FIG. 4, position detecting means 80 for detecting positions of the sliders SR or the sliding blocks are disposed between the sliders SR or the sliding blocks SB used at the first to the fifth bending roll units BR1-BR5 and the pair of bender frames 63, the movable blocks MB or the rotating fork 73 guiding the sliders SR or the sliding blocks SB.

The position detecting means 80 includes a marking needle 87 and a graduated ruler 89. The marking needle 87 is mounted at a side of the slider SR or the sliding block SB, and the graduated ruler 89 is attached to the pair of bender frames 63, the movable blocks MB or the rotating fork 73 corresponding to the marking needle 87.

In addition, a stopper 90 for restricting rotating angle of the rotating fork 73 is mounted at an upper portion of the rearmost bender frame 63. The stopper 90 includes a stopper ring 91 and a stopper rod 93. An end portion of the stopper rod 93 is mounted at the bender frame 63 and the stopper ring 91 is mounted at the other end portion of the stopper rod 93. The stopper ring 91 is positioned at the rear of the rotating bar 79 of the rotating fork 73 and is adapted to support a rear surface of the rotating bar 79.

In addition, referring to FIG. 5, power delivery means are mounted at the lower bending rolls LR1-LR5 of the first to the fifth bending roll units BR1-BR5 and deliver the power therebetween.

The power delivery means includes sprocket SP and chains C. The sprockets SP are mounted at end portions of the rotational shafts S of the first to the fifth lower bending rolls LR1-LR5 at an outer of one bender frame 63, and the chains C connect the sprockets SP.

The power delivery means according to an exemplary embodiment of the present invention include the chains and the sprockets, but are not limited thereto. Pulleys and belts instead of the sprockets SP and the chains C may be used as the power delivery means.

The fifth bending roll unit BR5 is not connected to the fourth bending roll unit BR4 through the chain C and is operated by movement of the shaped beam 30 in a normal condition. In a case that supply of the shaped beam 30 is finished, however, the fifth bending roll unit BR5 is temporarily connected to the fourth bending roll unit BR4 through the chain C and receive power from the fourth bending roll unit BR4 so as to push the end portion of the shaped beam 30.

Operation of the round bender 6 according to an exemplary embodiment of the present invention will be described in detail with reference to FIG. 8 to FIG. 10.

As shown in FIG. 8, the round bender 6 according to an exemplary embodiment of the present invention is disposed at the rear of the laser welding device 5 of the roll forming system in the process line, and is adapted to bent the shaped beam 40 to have different curvatures at the middle portion and both end portions thereof when the shaped beam 30 supplied from the laser welding device 5 passes through the first to the fifth bending roll units BR1-BR5.

That is, the shaped beam 30 is guided by the first upper bending roll UR1 and the first lower bending roll LR1 of the first bending roll unit BR1 and is slidably supported by the second upper bending roll UR2 and the second lower bending roll LR2 of the second bending roll unit BR2 along the curvature direction.

After that, the shaped beam 30 is formed to have the predetermined curvature when passing through the third, fourth, and fifth bending roll units BR3, BR4, and BR5. In a case that curvature radius of some portion of the shaped beam 30 is to be smaller than that of other portion of the shaped beam 30, the cylinder 71 moves to the rearward as shown in FIG. 9.

In this case, the rotating fork 73 is rotated about the rotational shaft S of the fifth upper bending roll UR5 by a predetermined angle θ, and thus the fifth lower bending roll LR5 is rotated with reference to the fifth upper bending roll UR5 to the rearward in the process line.

At this state, the some portion of the shaped beam 30 passes between the fifth upper bending roll UR5 and the fifth lower bending roll LR5 of the fifth bending roll unit BR5. At this time, the some portion of the shaped beam 30 has a smaller curvature radius than that of other portion of the shaped beam 30.

Therefore, if the shaped beam 30 should have multiple curvatures, curvatures of the shaped beam 30 can be controlled by forward/rearward operation of the cylinder 71. Therefore, a bumper beam 50, shown in FIG. 3, including a first curvature portion 51 having a first curvature radius at a middle portion thereof and a second curvature portion 52 having a second curvature radius that is smaller than the first curvature radius at both end portions thereof can be manufactured in one process.

If dimensions of the shaped beam 30 is different or curvature of the shaped beam 30 should be adjusted, a position of the fifth bending roll unit BR5 is changed. So as to change the position of the fifth bending roll unit BR5, as shown in FIG. 10, the adjusting bolt AB of the slider SR where the rotational shaft S of the fifth upper bending roll UR5 is mounted is controlled so as to control a position of the slider SR.

In this case, the fifth upper bending roll UR5 is moved with the slider SR, and the fifth lower bending roll LR5 together with the rotating fork 73 is moved with a distance to the fifth upper bending roll UR5 being maintained.

A round bender according to an exemplary embodiment of the present invention can manufacture a shaped beam having a first curvature portion and a second curvature portion without mounting an additional bending unit.

Therefore, manufacturing process and cost may be reduced and installation cost for installing an additional bending unit may not be necessary.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 

What is claimed is:
 1. A round bender comprising a plurality of bending roll units disposed along a process line between a pair of bender frames so as to bend a straight shaped beam to have a curvature, wherein each of the plurality of bending roll units include upper and lower bending rolls rotating between the pair of bender frames and is adapted to bend the shaped beam to have the curvature when the shaped beam passes between the upper and lower bending rolls, and wherein a lower bending roll of a rearmost bending roll unit disposed on a rearmost part of the process line is configured to be rotatable with reference to an upper bending roll of the rearmost bending roll unit so as to change a curvature radius of some portion of the shaped beam.
 2. The round bender of claim 1, further comprising a curvature changing means rotating the lower bending roll of the rearmost bending roll unit with reference to the upper bending roll of the rearmost bending roll unit, wherein the curvature changing means are disposed at the rearmost bending roll unit between the pair of bender frames such that a rotational shaft of the upper bending roll is rotatably supported at the pair of bender frames, and a rotational shaft of the lower bending roll is movably disposed in a penetration hole formed at the pair of bender frames.
 3. The round bender of claim 2, wherein the curvature changing means comprise: a cylinder disposed at a middle portion above the pair of bender frames, and hinged to the pair of bender frames through a hinge bracket; and a rotating fork having an upper end hinged to a rod of the cylinder, and connected to the rotational shafts of the upper and lower bending rolls of the rearmost bending roll unit at an outer of the pair of bender frames so as to rotate the rotational shaft of the lower bending roll in the penetration hole with respect to the rotational shaft of the upper bending roll according to operation of the cylinder.
 4. The round bender of claim 3, wherein the rotating fork comprises: a connecting bar disposed above the pair of bender frames and having a hinge end protruded from a middle portion of an upper surface of the connecting bar and hinged to the rod of the cylinder; and a pair of rotating bars disposed at the outer of the pair of bender frames corresponding to the rearmost bending roll unit, wherein an upper end of the rotating bar is connected to an end of the connecting bar, the rotational shaft of the upper bending roll is rotatably mounted at an upper portion of the rotating bar, and a slide hole is formed at a lower portion of the rotating bar such that the rotational shaft of the lower bending roll is rotatably mounted at a slider slidably mounted in the slide hole.
 5. The round bender of claim 3, wherein the rotational shaft of the upper bending roll is rotatably mounted at a sliding block slidably mounted in a slide recess formed at an upper portion of the bender frame.
 6. A round bender for bending a straight shaped beam to have a curvature, comprising: a pair of bender frames mounted apart from each other on both sides of a base; a first bending roll unit including an upper bending roll and a lower bending roll, disposed at a front portion on a process line between the pair of bender frames, and guiding the shaped beam; a second bending roll unit including an upper bending roll and a lower bending roll, disposed at the rear of the first bending roll unit between the pair of bender frames, and slidably supporting the shaped beam along a curvature direction; third, fourth, and fifth bending roll units respectively including an upper bending roll and a lower bending roll, sequentially disposed at the rear of the second bending roll unit between the pair of bender frames along the curvature, and forming the shaped beam to have a predetermined curvature when the shaped beam passes therethrough; and a curvature changing means disposed between the bender frame and the fifth bending roll unit and rotating the lower bending roll of the fifth bending roll unit with reference to the upper bending roll of the fifth bending roll unit so as to change a curvature radius of some portion of the shaped beam.
 7. The round bender of claim 6, wherein the curvature changing means is mounted at the fifth bending roll unit between the pair of bender frames such that a rotational shaft of the upper bending roll is rotatably supported at the pair of bender frames, and a rotational shaft of the lower bending roll is movably disposed in a penetration hole formed at the pair of bender frames.
 8. The round bender of claim 7, wherein the curvature changing means comprise: a cylinder disposed at a middle portion above the pair of bender frames, and hinged to the pair of bender frames through a hinge bracket; and a rotating fork having an upper end hinged to a rod of the cylinder, and connected to the rotational shafts of the upper and lower bending rolls of the fifth bending roll unit at an outer of the pair of bender frames so as to rotate the rotational shaft of the lower bending roll in the penetration hole with respect to the rotational shaft of the upper bending roll according to operation of the cylinder.
 9. The round bender of claim 8, wherein the rotating fork comprises: a connecting bar disposed above the pair of bender frames and having a hinge end protruded from a middle portion of an upper surface of the connecting bar and hinged to the rod of the cylinder; and a pair of rotating bars disposed at the outer of the pair of bender frames corresponding to the fifth bending roll unit, wherein an upper end of the rotating bar is connected to an end of the connecting bar, the rotational shaft of the upper bending roll is rotatably mounted at an upper portion of the rotating bar, and a slide hole is formed at a lower portion of the rotating bar such that the rotational shaft of the lower bending roll is rotatably mounted at a slider slidably mounted in the slide hole.
 10. The round bender of claim 8, wherein the rotational shaft of the upper bending roll of the fifth bending roll unit is rotatably mounted at a sliding block slidably mounted in a slide recess formed at an upper portion of the bender frame.
 11. A round bender comprising at least three bending roll units disposed along a process line between a pair of bender frames so as to bend a straight shaped beam and including upper and lower bending rolls, wherein a lower bending roll of a rearmost bending roll unit on a process line is configured to be rotatable with reference to an upper bending roll of the rearmost bending roll unit so as to change a curvature radius of some portion of the shaped beam.
 12. The round bender of claim 11, further comprising a curvature changing means rotating the lower bending roll of the rearmost bending roll unit with reference to the upper bending roll of the rearmost bending roll unit, wherein the curvature changing means are disposed at the rearmost bending roll unit between the pair of bender frames such that a rotational shaft of the upper bending roll is rotatably supported at the pair of bender frames, and a rotational shaft of the lower bending roll is movably disposed in a penetration hole formed at the pair of bender frames.
 13. The round bender of claim 12, wherein the curvature changing means comprise: a cylinder disposed at a middle portion above the pair of bender frames, and hinged to the pair of bender frames through a hinge bracket; and a rotating fork having an upper end hinged to a rod of the cylinder, and connected to the rotational shafts of the upper and lower bending rolls of the rearmost bending roll unit at an outer of the pair of bender frames so as to rotate the rotational shaft of the lower bending roll in the penetration hole with respect to the rotational shaft of the upper bending roll according to operation of the cylinder.
 14. The round bender of claim 13, wherein the rotating fork comprises: a connecting bar disposed above the pair of bender frames and having a hinge end protruded from a middle portion of an upper surface of the connecting bar and hinged to the rod of the cylinder; and a pair of rotating bars disposed at the outer of the pair of bender frames corresponding to the rearmost bending roll unit, wherein an upper end of the rotating bar is connected to an end of the connecting bar, the rotational shaft of the upper bending roll is rotatably mounted at an upper portion of the rotating bar, and a slide hole is formed at a lower portion of the rotating bar such that the rotational shaft of the lower bending roll is rotatably mounted at a slider slidably mounted in the slide hole.
 15. The round bender of claim 13, wherein the rotational shaft of the upper bending roll is rotatably mounted at a sliding block slidably mounted in a slide recess formed at an upper portion of the bender frame.
 16. The round bender of claim 1, further comprising power delivery means mounted at the lower bending rolls of the bending roll units and delivering power therebetween.
 17. The round bender of claim 6, further comprising power delivery means mounted at the lower bending rolls of the first to the fifth bending roll units and delivering power therebetween.
 18. The round bender of claim 11, further comprising power delivery means mounted at the lower bending rolls of the bending roll units and delivering power therebetween.
 19. The round bender of claim 10, wherein position detecting means for detecting a position of a slider block is disposed between the sliding block used at the fifth bending roll unit and the bender frame guiding the sliding block.
 20. The round bender of claim 19, wherein the position detecting means comprise: a marking needle mounted at the sliding block; and a graduated ruler attached to the bender frame corresponding to the marking needle. 